Labour MPs have expressed private frustration that Keir Starmer’s pledge to resign if he is fined by Durham constabulary for the Beergate investigation will lead to leadership jostling among ambitious shadow ministers. Both Starmer and his deputy, Angela Rayner, were at the event at Durham Miners Hall where a takeaway curry for the MPs and their aides is now subject to an investigation into whether it was a social event banned under Covid-19 rules in place in April last year. Starmer has said no rules were broken and that staff ate while working on an election campaign. Sources said Starmer told aides he wanted to announce he was prepared to resign three days before they agreed with his judgment, after days of anguish in his top team led the frustrated Labour leader to seek outside counsel from former advisers. The majority of shadow ministers said they were grimly resigned to Starmer’s pledge – but said there were likely to be internal consequences. “I think once you start talking up the prospect of your own resignation you are on dangerous ground,” one said. Another veteran MP, a Starmer loyalist, said they suspected ulterior motives from some shadow cabinet members. “If you fancy Keir’s job, this is win-win,” they said. Rule changes pushed through at last year’s Labour conference mean a fifth of MPs must nominate any candidate for the party leadership in order for them to be put to a members’ postal vote – a higher threshold than under Jeremy Corbyn’s leadership and a move that was seen by those on the left as intending to disadvantage their candidates. One MP said a snap leadership contest would put ascendant shadow cabinet ministers such as Wes Streeting, the shadow health secretary, in an advantageous position. “[Starmer’s] disappearance now would obviously benefit the Blairite right – [the mayor of Greater Manchester, Andy] Burnham couldn’t stand, Sadiq Khan [the London mayor] couldn’t stand, Angela would be out of the picture for the same reason as Keir because if he goes on this she has said she will go too.” If both Starmer and Rayner are forced to resign, there is no obvious interim leader. The most senior members of Starmer’s shadow cabinet – Rachel Reeves, the shadow chancellor; Yvette Cooper, the shadow home secretary; David Lammy, the shadow foreign secretary; Streeting; and Lisa Nandy, the shadow levelling up secretary – are all potential candidates in a contest. The party’s national executive committee would have to vote to designate an alternative member of the shadow cabinet. A source close to Starmer said he was relaxed about the ambitions of his shadow cabinet. “I don’t think anyone is actively trying to undermine him. It says a lot about our party that there are so many potential candidates – look at the contrast again with the Tories. If people are ambitious, let them be.” An ally of Streeting said: “Wes was on the media batting for Keir three times over the weekend and into Monday. He’s one of Keir’s most loyal and vocal supporters. After a great set of a local election results there is everything to play for at the next general election thanks to Keir’s leadership. This is no time for introspection.” Senior figures in the Labour leader’s team are understood to have felt reluctant to advise Starmer he should raise the prospect of his own resignation. On Friday, after finding out on Twitter that Durham constabulary intended to relaunch their investigation, Starmer told his core team of advisers he wanted to make the pledge to resign if fined and asked for their advice. Two of his closest advisers told him to sleep on it, and were not prepared to give him a strong fixed view, according to party sources. “It is fair to say Keir has not been getting the best advice he could and his own instincts were better,” one senior Labour source said. Starmer said he would not make an announcement on Saturday in order not to detract from the Scottish election results but was frustrated his team had been unable to form a clear view by Sunday afternoon when he returned from watching Arsenal. He began to ring friends – his former longtime aides Ben Nunn and Chris Ward, who left his team last year, as well as his inner circle of MPs, including Reeves. All of the shadow cabinet ministers and ex-advisers warned of the risk of fatal paralysis if he did not make the commitment. For now, his frontbenchers believe the heat is temporarily off. “It is frankly a statement of the obvious, which looks ballsy only because the PM has not been prepared to do the basic honourable thing,” one MP said. “Keir dug himself a big hole, and this was clearly the only way to get out of it,” another said. “Nevertheless it will make lots of people who don’t generally take much notice see him as a leader who is prepared to be decisive.”